Brake equalizer



May 7, 1929. GMER 1,711,886

BRAKE EQUALI ZER Filed April '7, 1924 Patented May 7, 1929.

cums G. GIITTER, OI SAN GABRIEL, CALIFORNIA.

BRAKE EQUALIZER.

Application filed April 7, 1924. Serial No. 704,719.

mg a plurality of cooperating brake drums.

While the invention may be embodied in 1 many different forms and used in various situations, it is particularly applicable to hoisting apparatus usedin connection with the drilling of oil or artesian wells. Therefore I have illustrated and will describe the invention as applied to this particular use, but this is not intended as an implication that the invention is in any way limited to such specific application.

Again, considering only the well drilling art, the invention maybe applied with equal advantage either to standard? or rotary drilling rigs, but I will confine this descrip: tion to a draw works installation wherein a winch or hoisting drum is utilized for raising and lowering drill or well pipe, fishing tools, etc.

Tools and well ipe are lowered and raised through a well bore by a cable which is trained upwardly and over a crown block at the top of the derrick or rig,

ried down to a power driven winch. The

drill ipe or casing is first setup on the derrick oor in stands, each stand consisting of several lengths of pipe coupled end to end By means of an elevator carried by the hoisting cable, the first stand is picked up from the floor and allowed to gravitate into the hole by giving the hoisting drum freedom of rotation. The speed of gravitation is controlled by the simultaneous application of braking force on the two brake drums with which the winch is provided, and the stand is finally brought to rest with its up er end protruding from the top of the well, y coinpletely braking the winch. Thereupon, slips are utilized to hold the stand while the elevator is released therefrom to pick up another stand which is subsequently coupled to the first. The slips are then removed an the two stands lowered, this process being continued until the entire string is lowered.

Of course, the weight of cable supported pipe increases directly as stands are added to the string, and when it is considered that there and then car-' may be several thousand feet of pipe to be lowered, say, eighty feet each time a stand is added, and the vertical movement of the easmg controlled and checked solely by brakingthe drum, it is obvious that a very considerable amount of heat is generated between brake drum and band, and that the wear and tear on the brake bands or their lining is very great.

These severe service conditions are aggravated b reason of the fact that in the usual type 0 WlIlCh it is impossible to exactly equahze the brakes, with the natural result that one brake is called upon to bear the brunt of the strain and receives much more wear than the other. This condition results in the necessity of frequently replacing the lining of the brake band which is subject to excessive wear, not only a most expensive procedure from the standpoint of material cost and time lost, but requiring readjustment of both brakes after each relining operation, since the new lining will be relatively thick while the partially worn lining of the other band is re atively thin. When it is remembered that the usual brake bands of a rig winch are nine feet or more in length, it will be realized that the purchase price of a lining 1s, in itself, a very considerable item, and further that the time consumed in each relining operation is suflicient to materially affect the ultimate cost of the well drilling operation, for the draw works and its crew must remain idle during periods of brake repair.

An unequal application of braking force results in the existence of uneven heat conditions throughout the extent of the drum, and the consequent uneven expansion of the drum metal and the expansion of the air confined within the drum, causes strains to be set up which have resulted in drum explosions on more than one occasion known to me, these explosions bringing about the loss of life and property.

Furthermore, the uneven application of braking force tends to defeat one of the main purposes of providing a plurality of bands on each drum, for the major portion of the (1 work must be accomplished through a single band, and the operators control over the winch is accordingly limited to his efforts as applied to a single brake drum.

Therefore, I have provided means for equalizing the brakes to render them equally efficient and properly coordinated. My

' equalizer practically eliminates all the above liquid which is placed under pressure between the two pistons during brake application, and it follows that the fluid pressure in the two cylinders must come into equilibrium when the bands are contracted about their respective drums by movement of the common brake lever, with the result that the braking force on the several drums is applied equally, irrespective of any differential in the clearance between the several bands and their drums prior to brake application.

The y-ieldable anchoring of the bands has further beneficial results in that it has a cushioning effect, prevents harsh brake application, enables the driller to regulate the braking pressure more finely, and does not require a tense straining of the drillers arm to effectand maintain brake application. This is true whether the connection be applied to a single brake band acting alone or to a plurality of bands acting together.

As a further feature, I introduce a gage in the pressure line, the gage being calibrated in any suitable manner to indicate variable pressure, and by noting the variable pressure recorded when different work is supported by the hoisting cable, the gage serves as a weight indicator. This feature is of great value in determining whether or not a tool has become twisted off, or whether or not a fishing tool has picked up a lost tool or section of drill pipe. For instance, when the driller has lowered the string to bring the drill into operative position, he may lift and hold the string just off bottom and note the pressure indication of the gage. Should he later lift and hold the string and note that the gage indicates a drop in pressure, he is immediately warned that less force is required to support the string, leading to the obvious conclusion that the string has parted and that a portion thereof has been left on bottom.

Conversely, in a fishing job an increased weight indication serves to notify the driller that the lost tool has been caught by. the fishing tool and has become attached to the string so it may be withdrawn.

Another instance of advantageous use of weight indication, is in straight drilling, where the driller does not wish to allow the full weight of the string to bear on the drill. In such a case,-he keeps constant pressure on the brakes, thus relieving thetool from a olefinite portion of the string weight and decrees ing the speed with which the cutting tool may sink through the work. Having determined the braking force necessary to relieve the tool to the proper or desired degree he may keep this force constant bysuch regulation of the brakes as will maintain a constant gage indication.

Other features of novelty and objects of the invention will be set forth in the following detailed description, reference being bad to the accompanying drawings, inwhich Figure 1 is a somewhat diagrammatic View of a drilling rig, showing a hoisting winch in connection therewith.

Fig. 2 is an elevation of a winch equipped with my equalizer; and

Fig. 3 is a vertical section on line 3-3 of Figure 2.

In the drawings, the numeral 10 generally indicates a derrick on the platform or floor 11 of which is mounted a winch 12. Floor 11 may be considered as the base or support- 7 ing member. of the winch which latter includes a cable winding drum 13 having brake drums 14 and 15. A shaft 16 is journaled in bearings 17 on uprights 18 (which uprights may be the derrick columns) and serves to revolubly support the winch drum; and

power from a suitable source (not shown) may be transmitted to shaft 16'through any suitable drive connection.

Hoisting cable 19 is wrapped about the drum 13 and extends upwardly to the derrick top. It is then rove through crown block 20 and traveling block 21, the latter supporting book 22 from which the'circulating head (not attached by clevis 28 to cranks 29 on shaft-30.

Crank shaft 30 is journaled in the bearing 31 on floor 11 and is adapted to be rocked by brake lever 32.

The opposite end of each band has a clevis or attachment strap 33 through which are passed the bars 34 of U-bolts 35. 'Adjustably secured by nuts 36 to the lower extremities of the U-bolt legs are bridges 37 upon which pistons 38 and 39 are secured by bolts 40. In effect U-bolts 35 and bridges 37 combine to form longitudinally adjustable stirrups.

Pistons 38 and 39 are adapted to reciprocate within inverted cup cylinders 41 and 42, respectively, which cylinders have their up er ends closed by caps or end walls 43. he cylinders have lateral ears 45 which" are pierced at 46 to allow the free passa e of the U-bolt legs therethrough, and are a apt/ed to receive anchor bolts 47 extending upwardly from floor 11. Nuts 48 are threaded on bolt 47 above and below ears 45 and serve to support the cylinders in adjusted position with respect to the floor and pistons. Ifluad 50 (heavy machine oil, for 1nstance)-1s Introduced to the pressure chamber 50 of the cylinders (the chambers being defined by the walls and ends 43 of the cylinders and the tops of the pistons) in any suitable manner. I prefer to tap nip les 51 into the side walls of the cylinders or the purpose of so introducing the fluid. Oil cups 52 on the nipples serve to hold a reserve supply of fluid, the fluid flow from cups to cylinders being controlled by shut-01f valves 53. A pipe 54 extends from c linder to cylinder, opening into each cyliner at a point above the limit of the pistons upstroke.

It is obvious that when lever 32 1s swung in a counter-clockwise direction, as viewed in Figure 3, cranks 29 rock to the left, drawing bands 25 and 26 around respective drums and raising the pistons until the fluid in the pressure line is compressed to such an extent that further piston movement is retarded or checked, whereupon the bands contract about their drums to efi'ect a braking of the wmch.

Due to the connecting pipe between the fluid or pressure chambers of the two cylinders, the fluid, in effect, is compressed betweenthe two pistons and since the piston areas presented tothe fluid in each cylinder are equal, the braking force as exerted by the two brake bands cannot be other than equal, all inequalities in original clearance betweenbands and drums being compensated by the equalizer. I

Thus the pressure line in connection with the movable pistons, provides an eflicient equalizer that insures equal wear on the .brake band linings, even heating of the winch,

etc., all to the end of producing the beneficial results and eliminating the objectionable features ofeother winches as outlined in the fore part of this specification.

To insure a snug and fluid tight fit between pistons and cylinders, pistons 38 and 39 may be provided with leather cup packings 55, piston rings, or the like.

As the brake linings wear away and thus allow a gradual increase in the piston stroke, it is preferable that the supply of oil in the pressure line be replenished through nipple 51. In the event suflicient air has leaked into the cylinders to resist entry'of a new supply of fluid, one of the valves53 may be opened to bleed off this air as the fluid flows in through the other valve. If there has been no air leakage, cups 52 are filled, both valves 53 are opened, and the pistons are depressed to draw in the replenishing charge of fluid.

In certain instances it is desirable to use only sufiicient oil in the pressure line and fluid of the gage may be such vas will indicate that certain weights are capable of being fully supported by cable 19 when the gage hand stands at certain predetermined positions. As pointed out above, this knowledge may be used to advantage in determining whether or not the entire string of cable-supported pipe remains intact, whether ornot a lost tool or pipe section has been picked up by a fishing tool, and whether or not the full weight of the string bears on the drill.

It is to be understood that the drawings and description are merely illustrative of and not restrictive on the broader claims appended rangement, and design may be made without departing. from the spirit and scope of such claims.

I claim:

1. In a winch mounted on a support, a plurality of brake drums, a brake band for each drum, and a yieldable connection between the support and one end of each band; each of said connect-ions including two members caable of telescopic movement and defining tween them a pressure chamber, one of the members being anchored to the support, and the other member being connected to and movable with the band, means for regulating the telesco' ic stroke of the members; the pressure cham' rs of the several connections behereto, and various changes in structure, ar-

ing in communication and adapted to confine a pressure transmitting medium; and force applying means adapted to act on the other end of each band to apply the bands to their respective drums. l

2. In a winch mounted on a support, a plurality or brake drums,.a brake band for each drum, and a yieldable connection between the support and one end of each band; each of said connections including two members capable of telescopic movement and definin between them a ressure chamber, a valved inlet for the cham ers, one of the members being anchored to the support, and the other mem-' her being connected to and movable with the band; the pressure chambers of the several connections being in communication and adapted to confine a pressure transmitting medium; and force applying means adapted to act on the other end of each band to apply the bands to their respective drums.

In witness that I claim the foregoing I have hereunto subscribed my name this 29th day of 

